Method of and means for preventing corrosion of well tubing, casing, and working barrels



Nov. 30 1926. 1,608,709

PREVENTIM coRRosIoN 0F WELL TUBING, cAsING, AND WORKING BARRELS R. VAN A. MILLS METHOD OF AND MEANS FOR Filed Sept. 1C, 19244 2 Sheets-Sheet 2 V ll umu

ILE

INSULATION Cl//P Nov. 30,1926. 1,608,709

" VAN A. MILLS R. v METHOD qF AND MEANS FOR PREVENTING CORROSION 0F WELL TUBING,

1 cAsING, AND WORKING BARRELS.

Filed Sept. 1o, 1924 2 Sheets-Sheet 1 TUBING- PHCER r I H NSuLAfloru [i /6 IrusuLA-rao'nl ELEcTRoPolwvE MET- l m.. SLEEVE IruSuLA-rlom @Warmst Patented Nov. 30,'i192`6.

-UNITED sjrArEs PAIE-NI OFFICE.

n oNAL'D l.VAN AUxriN MILLS, or

SAN-DY srRING,-MABYLAND, AssIGNoB; To P E'rnn Q. NYCE, or WASHINGTON. DISTRICT or COLUMBIA.

METHOD o1-AND MEANS son PREVENTING o'oRRosIoN oF WELLTUBING, eAsING.,

' .AND wo'nxING BABRELS.

Application filed September 10, 1.524.v

The invention relates to a method of and means for protecting welltubing, easing,`

equipment in oil and gas wells 1s essentially,

anV electro-chemical process dependent upon galvanic. action where the metallic equipment. is .wet by water.

Galvanic action between tubing and casing is most serious where the tubing swings close to or against the casing.

The corrosion occurs on electro-positivel surfaces, that is to say, the surfaces from which an electric current leaves a metal and passes into an electrolyte like salt Water.

To stop this corrosion in oil and gas wells it is desirable to:

1L Space the tubing from the casing.

2. Render the equipmentelectro-negative.

3. Supply an electropositive material that will cori-ode in preference to the iron or other metal yin the equipment.

It is the purpose of this invention to accomplish thesel things.

The invention will be described under three headings, covering different phases of the invention. although all ythe features herein described cooperate to produce a unitary' result. namely the `prevention of corrosion.

The features which will now be discussed in detail' are (l) the insulating tubing spacers, (2) the electropositivemetal sleeve, and (3) the. metallic contact brush.

Tubing spacers.V

which it rests. The spacers may'also be held in place by friction, clamps, screws or any other suitable device. The spacers are made ofbakelite fiber or some like non-conducting material. They are circular disks perforated by holes to allow the passage of fluids' and having a hole in the center just large enough I for the snug passage 0f the tubing- Other first part of the invention Serial No. 737,010.

shapes of `non-conducting spacers may be used inthe spirit and embodiment of this which consists esscntial'ly'of a non-conducting tubing spacer.

T he "tubing spacers may be used with or without the other parts of the device hereinafterdescribed.

Eleczroposz'tzge metal sleeve.

Since corrosion occurs on 'an electro-positive surface, the second part of this invention consists of a sleeve of metal suchas zinc I`that is electrolpositive to iron and therefore when proper y placed in the galvanie system in the well is positive to the iron andrenders the iron electro-negative. The zinc, being the electropositive metal, is' corroded whereas the ironis protected at the expense of the'zinc. The zinc must be replaced from time to time, at intervals of from six months to a year, as it is consumed.

.By placing the zinc on the tubing and using spacersto prevent the zinc and the tubing from coming in Contact with thecasing, except where desired as for instance above4 the water level inside the well, it is possible to make the tubing with its superimposed zinc the positive electrode in the galvanic s vstem of which the casing is the negative electrode. Moreover, the .zinc on the tubing being electropositive with respect to the tubing, protects the tubing as Well as the easing. s. Y

Contact between the tubing and casing is made above the water level either through the casing head or through actual contact'between tubing and casingl in the well where the tubing swings against the casing, or through a special devicev hereinafter described.

For the working of this method of protectcn it is imperativeto have the best possible electrical contact between zinc and tubing and the best possible-electrical condue tivity in the tubing and casing throughout the galvanic circuit. It is also. imperative to prevent short circuiting between-the zinc and the casing vand between the tubing and casing below the water level. for such short v"circuiting will consume zinc unnecessarily vvor cause corrosion or both. This is accomdrawings, in which y with a zinc sleeve constitutes the second part of this invention, a device for the protection of well tubingand casing against corrosion.

Metallic Contact brush.

Fig. l is a lView partly in sectiomand artly -in elevation showinor one form o -the protective sleeve appliedJ to well tubin the sleeve being equipped with insu ating spacers.

Fig. v2 is a plan view of the constructidn shown in Fig. 1, spacer. Figs. 3 and 4 are details in elevation and looking down upon the jplan, respectivelyf showing the'. Vtubing spacers.

Fig. 5 is a detail view showmg a spring washer to be applied at the-top 0f the proa modified form te'ctive sleeve, and s ervin to maintain electrical contact between t 1e .sleeve and the tubing.v j -1 Fig. 6 is a view similar to FigJd showin of the electropositi've meta sleeve. v u

. Fig.l 7 is a detail view showing a modified form of tie rod for sccuringtogethcr the but not from the calsing.

protective sleeve andispacing elements.

Fig. 8 is an elevation showing another modification of the protective sleeve wherein the sleeve is spaced away from the tubing,

Fig. 9 .represents a further modification ofthe zinc sleeve wherein aispace is provided between the sleeve and thetubing adapted to receiveniolten' metal or other material makingacast or welded connection between the zin'c and' the tubing.

Fig. 10 is a diagrammatic view showing I the galvanic circuit which exists in a well employing the lectropositive metal sleeve in connection with the `:veil tubing. f

Fig. 11 isa similar view 'showing-thev circuit where a special metallic contact brush Fig.` 12 is afdetail view showing one form of contact brush, and

l Fi 13 is. a view similar to Fig. 12, but showing a different form of contact brush..

According to the presentinvention, sleeves of zinc (ox" other "metal which* is .electropositive with respectto iron), are tted overl the tubing so as to bein contact with the rent passesl tubing but spaced away/from tlie casing so as to prevent direct 'contact therewith. The

term electropositive metal as herein used signifies a metal from which an electric curthrough a-nelectrolyte to iron or some o er metal with which the electropositive metal forms a galvanic couple. 4I nsulating spacers at the ends of the' v.zi-nc sleeve and extending beyond the zinc sleeve are provided to protect the zinc against impact and abrasion and to prevent the zine from swinging against the-casing.

t 'By' spacing the zinc awaylfrom the-casing, short circuiting between the -zinc and the casing, and theconsequently excessive consumption ot" the'zinc are prevented.

'llezinc'sleeve being eleetropositive with i respect to both' the tubing to 'which .it -is 'attached and the casingwith which it 1s 1n I closeproxilnity, serves to prevent corrosion of both the tubing andthe casing', the zine` itself fbei'ngnttacked by the Acorrosion preference to the iron or steel.

reversed, so that the zinc sleeve though at- The 'arrangement described ,above may bel tached to the tubing is in contact with the t casing but not with the tubing. f It will be `further; understood that aiiy desired number of the'protecting sleeves may be employed without departing fron the' spiritv ofthe present invention.

-Beferringparticularly to Figs. 1 and 2,

thereference numeral 10 indicates the tubing in a well (oil well or an`y other kind of well) which is normally subjected to the lcorrosive action of liquids and gasesf, -the usual tubing collar being indicated at 11. The well casing meral12.'

' In order to prevent corrosion of the tubing is indicatedfby the "-'nu-v and casing, a sleeve 13 composed principally a of zinc or other metal which is electropositive with respect to iron, is fitted over the tubing and rests upon the spacer 14. The internal diameter ofythe sleeve 4is .sutiicient to allow the tubing to pass through freely so'thatthesle'eve may be easily slipped on tothe tubing.

'The block of zinc-13 is preferably pro-l.

'tected at both ends bv means of circular spacers -14 of bakelite, fiber or other vlike iny lio sulating material which prevents the zinc from swinging against the casing,4 the diameters of the'v spacers being greater 'than the diameter of 'the 'zinc sleeve. The spacers -M'may vbe held iii-.place merely by gravity or inav be secured to the zinc sleeve in `any.

suitable mannenA as'b'y meansofl tie'bolts Thebottom spacer rests` by gravity on i top of the tubing colla-r, the zinc resting on top of the spacer.v

Inmany instances it may befoiind desirable to provide shoulders 20 upon the tie rods 15 in order to hold, the spacers 14 ml 130 spaced relation even after tho-zinc sleeves .einploved without departing from the spirit 'of the invention.

\ preferably of such size as to fit loosely withthe Casing? Sai 'embodiments of the invention.

` electrolyte 23 (saline water or other corro thercfro L f 7. The method 'of protectin well tubing f the tubing 10.

1,608,709 i l3j 1 3 have disintegrated due to corrosive ac- One form of contact brush is 'shown in detion. This arrangement is shown in Fig. 7. tail in Fi 12. ,According tofthis embodi- Preferably, also, a spring sleeve 16l is ment of t e invention resilient metal wires provided at the top of the zinc sleeve 13, 30 are inserted through holes 31 in# a-metal ections 17 extending a short dis- Y sleeve 32 surrounding the well tubing 10.l

having pro] tance into the space between the zin'c and These wires are bent to U-sliape and make a the tubing, \vlieieby :i good velectrical congood electrical Contact 'between the tubing tact is secured and looseness of the zinc 10 und casing 12.

sleeve is prevented. 1 A simpler forni of Contact brush 'is shown lVhilc the invention has been described in Fig. 13 in which wires 33 are merely in detail, for the purpose of illustration, it twisted labout the tubing 10, and if desired,

is obvious that many modifications may be may be spot welded ythereto as at 34, or fastened together to make a wire sleeve fitting around the tubing.y Y

F01 iexamplg, in Fig. 6, is shown un :ir- The invention has been described in great rangement consisting merely of a plurality detailfor- -the purpose of illustratioinbut it of zinc castings 18 surrounding the tubingl ViS evident that it. S 'Subject t0 many modi- 10, spacing ineinbers 14 being provided belCiltOnS Within the SCOpe 0f the appended tween the zinccastings as shown. claims.

Where the devi-ce isused in connection iI claim with oil wells. it is desirable to .provide 1 metllOd Of4 Preventing, Corrosion of means to permittlie free passage of gas or Well tubing and casing which consists in prooth'er fluids between tubing and casing. Aevidingnon-conducting spacing rings between l i cordingly, the spacers 14 are provided with Said' tubing and casing, whereby said tubing a plurality' of holes fluids. i E against said casing.

Another modification of the devicewhioh falls within the scope of the-invention is tubing and casing comprising a'plura'litybf shown in Fig. 8, According to this ar- V4non-conducting; spacing rings secured at 1nrangement, the zinc sleeve 13 is complet/ely `tervals upon said tubing to prevent the tubinsulated from they tubing by means 0f a ing from 'swinging against said casing, said 19 for the passage 0f is prevented from Swinging close to or' 2. 'Meansfor preventing corrosion of well.'

sleeve 21 ofbakelite fiber or other insulating spacers being perforated to permit lpassage material which may be formed integralwith 0f fllldthe bakelite spacer `14. According t0 'this In combination with well tubing and arrangement, the zinc sleeved may be of 08mg, a plurality: of non-conductmg spacgreater diameter than the spacer v14:, and is ing rings intcrosed between-said tubing and ring being provided with a. 1n the outer casingla: With this arrange-4v plurality of apertures t0 permit the passage ment, the insulation is located between the 0f lllld Vtubing and zinc/sleeve, rather than between 1 4l The" metllOd y0f #IJI'OteCting tubi-11g' the casing and the sleeve 'as in the previous against, corrosion which consists in providf Fig. 9 represents a further modification POS'VG With I'E'SpCtgtQ IOII, and Supplyin of the zinc sleeve wherein aspace 22 is roinsulatingv spacers above and below" sai vided between the sleeve 13 and the tu ing' metal sleeve. l 10 adapted to receive molten metal or other material making a casi; or welded comme- Aor casing against corrosion which consists tion between the zinc and the tubing. The in providing a metal sleeve composed ot purpose of ycasting or welding the Sleeve is material which is electropositive with reto give the best possible Contact between the spect to the tubing or casing in closeproxzinc and the tubing. f'

Rel'erring now to the diagrammatic repretherefrom. sentation `oft tthe galvanic circuitV shown in 6. The' method of protecting tubing or casin Fig. 10, it will be seen that theicurrent ing composed of ferrous'mateial which conllows in the direction of the arrows from siste in providing'a zinc sleeve in close prointhe electopositive metal' 13 through the imity to 'said tubing `or casing but spaced sive liquid) to the casing 12. The circuit is completed through the 4casing head 24 iiid against corrosion which consis 1n provid If desired, metallic contact brushes 25 as is electrofpositive with respect to the tubing shown in Fig. 11, may be used to complete and providing a nonconducting rspacer' bethe g'alvanic circuit above the water evel low said metal sleeve. .c v so as `to avoid the unnecessary long Circuit s. A method of protecting weil tubing mi through the' casing casing against corrosion which consists in ing said tubing with a sleeve of metal which ing said tubi-ng with va sleeve of metal electro- 5. The "methodof protecting-well tubing imity to said tubing or casing, but spaced.-

' interposing between said tubing .and casing kagainst corrosion which consists 1n supplya pluralit of sleeves composed of metal .whlch is eiectro-positive with respect t0 the tubing and casing, preventing short circuitmgbetween said tublng and casmg at said electro-positive Ysleeves by the use 0f suitable combination, a plurality of zinc s eeves sur-l rounding thc vtubing and .in contact there# l` i with located below the level v of the liquid in the Well, non-conducting spacing Arings of greater diameter than the'zinc foripreve'nting' contact between said sleeve and said casing, and contact devices above the vlevel ofthe liquid in the well l*for completing an eiectric circuit.v Il w,

11. The methodf yof protecting tubing ing a sleeve of metal which is electropositive to the tubing, in close proximity to the tubing. but spaced therefrom.y

`12. In combination with a Well tubing and casing, a plurality -ot zinc castings surrounding'sajd tubing at intervals, land bakelite, fiber or other spacing membersof greater diameter than the zinc castings interposed between the castings and designed to prevent said castings from swinging against said casing. v

`13. .In combination with a well-tubing and casing, a'zincsleeve surrounding theJ tubing jin close proximity thereto, but not in direct contact therewith, an insulating sleeve interp'osed between zinc and the tubing, a collar on said tubing, and an insulating spacer integral 4with said insulating sleeve, and

resting upon said. collar, said insulating `sleeve being of less diameter thanthe'zinc sleeve, `and said zinc sleeve `fitting closely Awithint'he outer casing.

In testimonywhereof I ag: my signa- ,y

ture.

YRONALD VAN AUKEN MILLS. 

